Wojciech Palacz

Algebraic hierarchical graph transformation

This paper presents a framework for constructing hierarchical (hyper)graphs, using one of the well-known categories of traditional flat (hyper)graphs as a base. Hierarchical graphs are obtained from flat graphs by adding a parent assigning function to them. Any graph atom (vertex or edge) can be assigned as a child of any other atom. Hierarchical graphs are more expressive than flat graphs, yet similar enough that the double-pushout approach to graph transformation can be extended to them.

Artefactual Reasoning in a Hypergraph-Based CAD System

This paper deals with a computer system supporting conceptual floor layout and reasoning about abstract spatial artefacts. The reasoning module is able to evaluate constraints which involve immaterial entities (range spaces of sensor devices). The internal data structures of the system are hypergraph-based, but the design constraints are specified as first-order logic formulae.

Conceptual Designing Supported by Automated Checking of Design Requirements and Constraints

This paper aims at contributing to a better understanding of essential concepts of supporting system for initial visual design. Towards this end, we first outline the system architecture corresponding to our model of conceptual design aided by computer, in which designer’s drawings created on the monitor screen are automatically transformed into elements of a graph-based data structure and next into the first-order logic formulas. Then, we describe particular modules of the proposed model paying attention to the role of a graph-based data structure gathering information on which design knowledge is based. Finally, the approach is illustrated on examples of designing floor layouts where fire code regulations and ranges of sensors are checked on the base of the proposed design knowledge reasoning module.

Towards collaborative creative design

Abstract The paper presents a design support system for collaborative work based upon the composite knowledge representation. It addresses the main challenges of distributed environment: ensuring a convenient access to the common data by multiple users and maintaining consistency of such data. The main idea is to couple the design support system implemented in C/C++ with the knowledge database using the ODBC library developed by the Microsoft. The ability of the proposed system is demonstrated on several examples.

Ontological Approach to Design Reasoning with the Use of Many-Sorted First-Order Logic

This paper is a continuation and extension in developing the knowledge-based decision support design system (called HSSDR) which communicates with the designer via drawings. Graph-based modeling of conceptualization in the CAD process, which enables the system to automatically transform design drawings into appropriate graph-based data structures, is considered. Hierarchical graphs with bonds are proposed as a representation of designs. An ontological commitment between design conceptualization and internal representations of solutions, which enables us to capture intended design models, is described. Moreover, the first-order logic (FOL) of HSSDR is replaced by many-sorted FOL that makes it possible to define different sorts in specification of functions and predicates in semantics and design constraint verification.

Hierarchical graph transformations with meta-rules

This paper is concerned with hierarchical graph models and graph transformation rules, specifically with the problem of transforming a part of graph which may contain subordinated nodes and edges. Meta-rules are proposed as a formal way of representing transformations which remove or duplicate a node along with its contents. The paper discusses the behaviour of meta-rules when applied to different types of hierarchical graphs, possible failure cases, and concludes by introducing a type of hierarchical graphs in which meta-rules can always be successfully expanded.

A graph-based generation of virtual grids

This paper presents a unified formal model to be used in the grid representation based on hierarchical graph structures. It aims at both helping in a better understanding of grid generation and in grid simulation problems. A new graph structure called layered graphs is proposed. This approach enables one to use attributed graph grammars as a tool to generate both a grid structure and its parameters at the same time. To illustrate the method an example of a grid generated by means of graph grammar rules is presented.

ON USING GRAPHGRAMMARSAND ARTIFICIAL EVOLUTION TOSIMULATE AND VISUALIZE THE GROWTH PROCESS OF PLANTS

In this paper we propose a hierarchical approach to representing plants and their environment. The graph grammar is used to simulate the growth process of each plant. This approach is combined with an artificial evolution that models the growth of the whole environment. The proposed approach is illustrated with an example of a set of fern-like structures.

Decision Making in Building Maintenance Using a Graph-Based Knowledge Representation

This paper is an attempt to support effective decision making in building management by assisting maintenance processes. Knowledge about buildings is stored in a graph with many hierarchies. This representation allows us to express different types of hierarchical dependencies between building parts, like geometrical and functional ones, in one structure. Moreover, such a structure is useful to extract subgraphs containing information necessary for a given computational task, such as locating a desired place and the shortest path leading to it. As maintanance processes often require dynamic path target selection, modified indoor navigation methods are proposed. The paper presents the capability of the described knowledge model to cope with complex queries referring to different types of information. The considered examples show that the proposed approach can be used for various facility maintenance management applications.

Visual Design Using Case-Based Reasoning and Multi-agent Systems

This paper deals with case-based reasoning (CBR) which is adapted in the Computer Aided Design (CAD) system. The specialized CAD tools of the system allow the designer to visualize general ideas about projects in the form of design drawings and automatically transform them into graph data structures. The system’s library provides source cases representing previously created solutions. Designer’s requirements are represented by graph patterns and the case library is automatically searched for cases which fit these patterns. Target cases result from the cooperation among the human designer and intelligent software agents. The retrieved cases are evaluated on the basis of specific design knowledge the agents are equipped with. The presented approach is illustrated on the example of designing an indoor swimming pool.